This invention relates to a yarn product and to a method of making a yarn product.
It relates particularly to an untwisted single strand continuous yarn of fine garment/dress glove leather suitable for and used on knitting machinery for the purpose of making garments, especially ladies' fashions.
To obtain an understanding of the unique leather yarn of the present invention, a review of the general characteristics of yarns is helpful.
A yarn is a narrow, continuous strand of natural or synthetic material to be used for knitting, crocheting and associated arts.
The yarn is usually made from either a twisted aggregate of fibers spun out to considerable length or from some other ductile substance drawn out to suitable dimensions.
To better understand yarns, it is useful to look at the nature of fibers, the fundamental units used in the making of textile yarns and fabrics. Fibers are hair-like substances that are small in diameter in relation to their length. Examples are the fine hairs of the mature cotton ball and the fine secretions of the silk worm.
There are two basic forms of fibers. First there are staple fibers (natural and synthetic) giving spun yarns, e.g. cotton and rayon.
Secondly, there are filament fibers (natural and synthetic) giving continuous filament yarns, e.g. silk, nylon.
Staple fibers are a bunch of short fibers generally from 1/2 inch to 24 inches long that are later spun into a continuous strand held together by the inherent cohesive properties of the fiber, i.e. the wavy shape and irregular surfaces of each fiber that hook onto one another, when twisted and drawn out, forming a continuous line.
Filament fibers are individual fibers which are continuous or long in length to begin with, such as silk, the only natural filament fiber. A monofilament is a long, continuous, single fiber of high strength, such as a nylon fishing line. A multifilament is a number of fine monofilaments wound together to form a strand.
Many fibers abound in nature that are not used for making yarn because they lack the combination of properties that make yarns spinnable and suitable for yarn making. These properties include length, pliability, strength and cohesiveness.
Spinning is a series of mechanical operations designed to clean and parallel fibers, to draw them into a fine strand, and to twist them to make a spun yarn. Some fibers must go through all these operations. Others, such as silk, only go through the twisting and winding. There is also chemical spinning done by the extrusion of a substance solution (such as nylon) through a spinnaret into fine strands.
Silk alone is a natural continuous strand of length, and yet it is wound and twisted, for it is not indefinite in length, nor strong enough in a single strand for most purposes.
Of course, many fibers that are spinnable fail for other reasons -- availability, cost, etc.
Rawhide, the starting material for the yarn of the present invention, is technically neither a staple fiber nor a filament fiber, but is comprised of an aggregate of fibril material (dermis), surmounted with a smooth surface (epidermis). This aggregate of rawhide fibers inherently possesses the properties of cohesiveness, pliability, and strength. The only remaining characteristic of fiber (found suitable for making yarn) missing in rawhide is the long thin length. To achieve this property the rawhide is not spun, but instead is prepared to the standard tannage of fine garment/dress glove leather, and then undergoes a specialized cutting process that renders it into a long narrow thin continuous strand. Thus leather yarn is an aggregate of fibers held together by proteinous substances cut, instead of spun, into a long continuous untwisted single strand.
In this state, the present invention provides a strand of natural protein fiber (like silk and wool in this respect), which has the properties of a natural filament fiber such as silk, but which is larger in diameter with a "leather hand" and which has no need to be spun or twisted.
Although two other products (leather lace and leather strips used for macrame) have been commercially produced, neither has approached the workability characteristics of other ordinary yarn, nor the properties needed for knitting machinery, which the present invention has. The present invention provides a genuine continuous, uniform, untwisted single strand leather yarn (as will become more apparent from the description that follows) suitable for fine garment knitting on knitting machinery (fine garment as opposed to working garments).
The general concept of a leather yarn which can be used for hand or machine knitting is not novel. For example, U.S. Pat. No. 2,067,895 issued Jan. 19, 1937 to Ida Arbib, relates to a leather yarn product and points out that a leather yarn may be produced by a spiral cut from a soft, suede-like material. However, the Arbib patent discloses only the general concept of a leather yarn. The Arbib patent does not disclose the specific and interrelated characteristics that must be incorporated in a leather yarn product in order for the yarn to be commercial acceptable (and which characteristics become particularly critical in the case of a leather yarn to be used in machine knitting). The Arbib patent also fails to disclose specific techniques for enabling soft leather (required to provide sufficient flexibility in the yarn) to be cut to the narrow widths desired and with the uniformity required for fine garment knitting machinery while avoiding the major stumbling blocks (such, for example, as the pronounced tendency of soft leather to bunch up upon being cut) which are inherent in the cutting of soft leathers to narrow widths and close tolerances.
The problems encountered in producing a commercially acceptable leather yarn result from several reasons. These include the nature of the leather industry itself, the characteristics of the fine garment/dress leather, the relatively small size and the relatively high precision to which the leather yarn must be cut, and the necessity of removing deposits of tannage and natural oils and fibrous deposits from the cut yarn before use in knitting channels of knitting machines.
Traditionally many of the tanning companies are family owned, and the different tanners often use their own methods and modifications in their tannages; and there has been a distinct lack of objective criteria in the industry concerning leather. For example, different tanners have different color combinations and may make minor alterations to the basic tannage. There has been very little tensile strength testing apparatus for soft leather; because, until the present invention, there appeared no purpose for such apparatus. Softness indicators are also generally lacking and softness is instead based on subjective knowledge understood by those skilled in the trade. This subjective perception thus determines the category of the leather, such as, fine garment/dress glove leather.
After a leather having the required combination of softness and strength is obtained, it must be cut to the thickness and width dimensions of yarn which can be utilized in machine knitting operations. This requires, as a practical and economic matter, that a machine cutting operation has to be used. Hand cutting cannot maintain the tolerances required and is much too expensive.
Soft leather, because it is soft, tends to bunch easily in front of a cutting blade. This bunching tendency makes it difficult to cut soft leather to relatively narrow widths and to a relatively high uniformity or precision in the narrow widths. Any wrinkles or bunching passing the cutting blade cause either a break in the yarn or a distortion in the width. As a practical matter, to obtain the precise cutting of soft leathers to small widths, the surface area of the whole piece of leather to be cut must be secured, and the cut must be made with a sharp blade and without too large a differential between the relative speed of the blade and the piece of leather being cut along the direction of the cut and also without exerting too much of a stretching force on any part of the leather being cut.
To obtain the greatest length with minimum splices, the leather yarn is cut as a strip from the outer periphery, and this results in cutting the yarn from a piece of leather which continually gets smaller in diameter. The larger the diameter of the leather disc the greater the problems of bunching of the soft leather in front of the cutting blade become greater. The resistance to the ripple/wave effect increases as the uncut piece of leather gets smaller in diameter. Also, when the leather piece being cut is mounted on a turntable (so as to be rotated past a cutting blade at a fixed location of the cutting blade) and when the strand being cut is used to produce the rotation of the leather being cut, the leather circle spins faster and faster as it gets smaller to keep up with the constant take-off rate of the strand being cut. This pulling action also tends to cause elliptical circular cuts to build up in the leather disc, and this elliptical shape further tends to pass a doubled-up wrinkle past the cutting blade. As will be described in more detail below, the present invention overcomes these problems of the prior art by providing a temporary stiffening of the leather being cut, to minimize the tendency of the soft leather to bunch. Furthermore, the present invention provides the temporary stiffening in a way that permits the temporary stiffening to be readily removed after the cutting has been accomplished so that the cut leather yarn can reassume its natural soft state.
As noted above, the knitting channels of knitting machines are quite sensitive to becoming jammed by dirt and oil. When this occurs, the yarns can become caught and can break in the knitting channels; and this in turn causes down time of the machine. Leather, by its nature, has a certain amount of oiliness and fibrous material, and it is important for a commercially acceptable leather yarn that excess oil and loose fibrous material be removed from the surface of the yarn before the yarn is used with the knitting machines.
As will be described in greater detail below, the present invention provides, as a part of the manufacture of the yarn, an intentional amount of manipulation of the yarn which has the effect of scraping off excess oil and loose material. The present invention also provides for beveling cuts which help remove loose fibril material.
The knowledge (that was lacking in the prior art) to enable a commercially acceptable leather yarn to be produced with the size, uniformity of dimensions, tensile strength, softness characteristics, and freedom of deposits of tannage, natural oils and fibril materials, all as required for machine knitting operations, has been made available by the present invention.
U.S. Pat. No. 86,755 issued Feb. 9, 1869 to G. and D. Hurn illustrates, like the Arbib patent, the cutting of a leather strip from the outer periphery of a piece of leather. The piece cut is then woven, with another leather or vegetable fiber, into a fabric. While the Hurn patent does not specify the type of leather from which the strip is cut, it appears that the Hurn patent relates to the cutting of a relatively hard leather because the patent mentions the subsequent use of the woven fabric as driving belts and harness strips and also because the patent refers to removing abrupt angles and curves from the cut strip by stretching, dampening, greasing, rolling, hammering and other equivalent operations on the cut strip. Abrupt angles and curves indicate that the cut strip of the Hurn patent is neither consistent nor uniform, and these are characteristics which are essential for a machine knitable leather yarn. The Hurn patent, like the Arbib patent, lacks any showing or suggestion of detailed specifications and descriptions of cutting operations and techniques required to produce a commercially acceptable machine knitable leather yarn. The Hurn patent instead appears to be directed to leather cutting of lace leather.
The leathers used for making lace leather are often quite thin, and the weight of such leathers can be made lighter for the corresponding skin size than the weight of garment leather. This is so because lace leathers are treated with chemicals and/or machines which maintain or reinforce both the tensile strength and the rigidity of the leather. This produces however, a very stiff leather, which happens to be a desirable quality for its intended purpose. The stiffness provides a sturdiness which allows the subsequent lace cutting process to work. Thus, while the lace product, after cutting, is a thin and narrow strip of leather, it is so stiff as to be well removed from any possible application as a yarn in a fabric knitted by needlework for fine clothing or on a knitting machine for similar purpose.
U.S. Pat. No. 2,781,532 issued Feb. 19, 1957 to H. H. Hoffman; U.S. Pat. No. 1,459,888 issued June 26, 1923 to M. D. Heyman and U.S. Pat. No. 1,937,399 issued Nov. 28, 1933 to W. Bateman are examples of lace leather cutting apparatus and methods and products. The lace leather products as produced by the Hoffman, Heyman and Bateman patent disclosures are not, as noted above, suitable for use as yarns in knitting machines.
U.S. Pat. No. 1,713,113 issued May 14, 1929 to W. M. Cavanaugh makes reference to a leather yarn product, but the description of the product makes it clear that the product described is not suitable for use as a yarn in a knitting machine. The yarn is described as a leather strip product of small length and having a width of 1/2 inch which is folded about inner fibrous threads to a tubular form. A number of such folded leather strips are aligned end to end and then twisted in a way such that a strand thus formed has a smooth leather outer surface for subsequent use in weaving in a loom. The relatively heavy, twisted yarns produced by the Cavanaugh patent process would necessarily have a resistance which defeats the soft pliability required for use as a yarn in a knitting machine, and any fabric made from such leather yarns would not be appropriate for fashion clothing.
Macrame is a course lace or fringe made by knotting threads or cords in a geometric pattern.
Macrameing is done by hand. The leathers that were made for knot tying had to be relatively soft and flexible. However, such leathers are not light weight and are not within the claimed dimensions of this invention.
It works against the use of leather for macrameing to make the leather too light weight. While (on first impression) the appearance of a macrame lace might have a superficial similarity to the leather yarn of the present invention, the macrame lace and this leather yarn are different products having sufficiently different physical characteristics that render macrame lace unsuitable for the needlework use of the yarn of the present invention. The macrame leather lace is too heavy to bend in the abrupt ways required for needlework such as crocheting and especially machine knitting. Macrame lace lacks the thinness and/or the narrowness, softness, or pliability which is required for the bending involved in needlework and knitting machinery. It also slows down crocheting considerably. Macrame leather lace is too heavy to bend in the way required for crocheting. Thus, fabric made from macrame lace does not have the hand or drape of a fabric knitted from the yarn of the present invention.